1. Field of the Invention
The present invention relates to a mechanical pencil in which a knock-lever mounted in a side wall of a barrel of the mechanical pencil having a chuck mechanism is knocked by a fingertip holding the barrel to draw out lead.
2. Description of the Prior art
FIG. 1 is a longitudinal sectional view showing a conventional side-knock type mechanical pencil. In this drawing, a barrel 11 is provided in the side wall thereof with an opening comprising a first opening portion 13a and a second opening portion 13b which are continuous through a fulcrum 12 formed at a contact position of a fingertip portion holding the barrel 11 during writing.
A knock lever 14 is mounted in the opening portions 13a and 13b. As shown in FIG. 2, the knock lever 14 is provided with a knock surface 15 knocked by a fingertip in order to draw out lead, a locking stepped surface 17 continuous to the knock surface 15 and in contact with a stepped surface wall 16 of the barrel 11 at the end of the second opening portion 13b to prevent the knock lever 14 from moving backward, a locking surface 18 continuous to the stepped surface 17 and in contact with an inner wall of the barrel 11 and a pair of acting flaps 24 inserted into the barrel 11, ends of which come in contact with an inclined surface 22 of a slider 21 provided on a joint 20, each of the acting flaps 24 being provided with a laterally projecting protrusion 26 to be locked at a locking stepped portion provided axially of the inner wall of the barrel 11.
The knock lever 14 is provided so that the locking surface 18 is inserted into the second opening portion 13b, and the locking stepped surface 17 is placed in contact with the stepped surface wall 16, the acting flaps 24 being pressed inward by a finger to press the knock surface 15 in an axial direction of the barrel 11 in a curved state, whereby the flange 26 is locked at the locking stepped portion.
The operation for drawing out lead in the prior art will be described hereinafter. The knock surface 15 is knocked whereby the acting flaps 24 come in contact with the inclined surface 22 of the slider 21 provided on the joint 20, the joint 20 is moved forward along the inner surface of the barrel 11 against a spring 23 to open the chuck mechanism 19 to enable drawing-out of lead.
Since the conventional side-knock type mechanical pencil is constructed as described above, mounting of the knock lever on the barrel is troublesome and requires skill. Further, since the knock lever is pressed in its extreme end portion into the barrel, and the inclined surface of the rear end portion of the slider is pushed by the extreme end portion to advance the slider, it was difficult to take a knock stroke sufficiently. As a result, the opening and closing operation of the chuck mechanism is possibly unreliable. Furthermore, since the knock lever causes the slider to operate directly by the pressing force thereof, the fingertip needs to have great force. In particular, in case of a slide type mechanical pencil of a pipe provided in a tip slide, that is, a tip member, the stroke for pushing out the pipe is necessary, which had been very inconvenient in a so-called inclined surface system making use of an inclined surface portion in prior art.
This invention has been accomplished in order to solve the problem as described above. It is an object of the invention to provide a side-knock type mechanical pencil which is easy in mounting a knock lever on a barrel, and which can take a large knock stroke with small operating force.